SOLUTION: in the equation y=2x?-5x-18, which is a value of x when y=0?

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Question 130874: in the equation y=2x?-5x-18, which is a value of x when y=0?
Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
2x^2-5x-18=0 I assume that this is the problem.
x=-2, x=-4.5 See below
.
Ed
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 2x%5E2%2B-5x%2B-18+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%28-5%29%5E2-4%2A2%2A-18=169.

Discriminant d=169 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--5%2B-sqrt%28+169+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-5%29%2Bsqrt%28+169+%29%29%2F2%5C2+=+4.5
x%5B2%5D+=+%28-%28-5%29-sqrt%28+169+%29%29%2F2%5C2+=+-2

Quadratic expression 2x%5E2%2B-5x%2B-18 can be factored:
2x%5E2%2B-5x%2B-18+=+%28x-4.5%29%2A%28x--2%29
Again, the answer is: 4.5, -2. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+2%2Ax%5E2%2B-5%2Ax%2B-18+%29